The invention relates to a data transmission system having several devices connected to one another by electrical lines, data transmission being possible in both directions between the devices which have at least one data output and one data input separated from the data output.
Systems of this type may be pure data transmission systems or also, however, data processing systems. Because the levels of the digital signals are defined for systems of this type, measures must be taken to ensure that when devices of the data transmission system which are spatially separated from one another are connected by means of electrical lines or cables, all devices connected to one another are at the same ground potential. The satisfaction of this requirement is occasionally difficult, so that a risk of interference in the data transmission arises. It is accordingly an object of the invention to provide such a data transmission system with relatively simple means which avoid such interference.